Wordcheckernational (adjective): relating to a nation or countryflag (noun): piece of cloth used as a symbol of a countryserve (verb): perform; have; be of use in achievingpurpose (noun): reason for which something existsnowadays (adverb): today in contrast to the past; these daysuseless (adjective): unable to achieve an intended purpose

I don't think flags are completely useless. The essential purpose of flags I think is to able to identify its holders. And sometimes you may encounter a situation when other means of identification are impossible, particularly when you're in the long distance. In this case, you can't see what is written over-there (on a ship, for instance), also when is to difficult to see an emblem or recognize sound. So, as you see, some narrow use of it do exist.